1. Field of the Invention
The present invention generally relates to the culinary arts and more particularly to an improved type of flexible culinary sheet and pan liner formed therefrom.
2. Prior Art
Various types of flexible sheets have been devised in the past for wrapping foods and/or for cooking and/or warming foods therein or in pans, trays or the like provided with liners made from such sheets. For example, paper sheets of cellulosic fibers have been used, as well as various types of thermoplastic and thermosetting films. Moreover, thin metal foils, so-called tin foils, which are in reality thin sheets of aluminum, are extensively used for cooking, heating and storing foods.
Various difficulties have arisen through the use of such sheets, films and liners made therefrom. For example, metal foils are notoriously easy to crack and break, so that foods wrapped therein frequently are not fully protected by the foil. Such foil is not easy to wrap closely around irregularly shaped roasts and the like, so that air gaps frequently remain between the foil and the food, leading to changes in taste in the food and eventual spoilage.
While paper sheets are useful for a variety of culinary purposes, their moisture and air transmissibility allow rapid spoilage of food wrapped therein. Accordingly, usually such thin plastic films as polyvinylidene chloride films, sold under the registered trademarks SARAN and CLING WRAP, are preferred for wrapping and preserving foods. However, such films stick to themselves and are difficult to handle and manage and are also very fragile.
Thermoplastic films with slightly greater durability such as polyethylene films and the like are extensively used for wrapping, storing and warming foods. Some of such films are opaque or translucent and therefore not very appealing.
Because each of the above-listed types of sheets or films has a number of drawbacks, certain recent inventions have been directed to providing combinations of such sheets and films. The results are generally expensive and still do not offer optimal properties. For example, those multi-layered combinations which employ metal foil sheets are still subject to breakage of the foil and ultimate failure to protect the foods disposed therein.
One such multi-layer, foil-containing wrapper is illustrated in U.S. Pat. No. 1,885,670 as a food bag or the like. Multi-layered plastic sheets are shown in U.S. Pat. No. 2,715,089. U.S. Pat. No. 4,965,135 shows similar multi-layered plastic sheet constructions. A cellulosic pad with a thermoplastic perforated film laminated thereto is shown in U.S. Pat. No. 3,320,075. A combination sheet employing a sheet of metal foil laminated to a cellulosic or rubber sheet is shown in U.S. Pat. No. 2,003,494. A fusible strip laminating two sheets of metal foil to each other is shown in U.S. Pat. No. 2,069,335. U.S. Pat. No. 2,150,058 discloses the use of a metal foil sheet with a surface coating of vinyl resin. U.S. Pat. No. 1,983,520 shows paper or plastic film laminated to a metal foil strip by wax.
A pan liner for pies and the like is formed of perforated metal foil connected to a cellulosic fiber layer (see U.S. Pat. No. 3,411,433). Various fluted and/or perforated metal foil pie pans and liners are shown in U.S. Pat. Nos. 2,802,411 and 2,570,060, as well as 2,027,296.
Despite the great diversity of combinations of metal foil, plastic films and/or cellulosic fiber paper, there remains a need for a simple, flexible, resilient, durable, culinary sheet and a pan liner made therefrom which sheet and liner have controlled thermal and other characteristics and are not subject to breakage during use.